Skin, muscle, bone, how deep is your writing?

Skin—You have the story locked inside of you, like Michelangelo’s David was once locked in a block of Carrara marble. You envision it. You have not started to sculpt and whittle away. How many of us never venture beyond scratching the surface?
Muscle—You know the story. You have started to carve it out, to whittle, shape, and remove the obstacles of doubt and uncertainty. But doubt and uncertainty still block you. Your writing muscle tires. You walk away and think of starting over. How many come back and muscle through?
Bone—You have gone the distance, done the ant work, the trench work, pulled forth what you know is there, your magnificent work. Maybe you have entered the piece from various of the Seven Entry Points. It’s a work in progress, but it’s there, bared to the naked eye. You love it. Still, some doubt and uncertainty.
Marrow—You’ve cut through skin, muscle, and bone, through cartilage and ligament. You’ve bled interminably. You’ve gone beyond doubt and uncertainty. You’re drained, flushed of all—blood, sweat, tears, emotions.